© Opticstar Ltd / Ascension 2007-2014
17
APPENDIX B: Optics
Optics Care
Lenses and corrector plates can be treated as
camera lenses for cleaning purposes. What
makes them difficult to clean is the large size of
such optical elements.
The general rule is not to touch the optics and
only clean them when absolutely necessary; dust
on the objective lens could be removed with very
gentle strokes of a camel hair brush available at
camera shops.
Another way to remove dust from an optical surface is with compressed
photographic air which is free of contaminants. Be careful and always make
certain that the nozzle is propellant free. Hold the compressed air-can the
right way up as otherwise they can discharge liquid propellant which will
stain the optics. Stains on optics can be removed with optical cleaners used
to clean photographic lenses. Always use compressed air at very low
pressure as contaminants that may have landed on the lens could scratch
the glass surface, never rush the cleaning process.
Condensation
When temperature drops rapidly condensation may form on the objective
lens of the telescope. This happens over time and its effects become
noticeable as condensation builds up and the target becomes dimmer and
appears as if it is out of focus.
Condensation can be removed from the optics with a hair-
dryer set to ‘cold’.
Otherwise bring the telescope inside and let condensation to dissipate
before putting on the cover. Place the telescope on a table and not on the
floor where most of the dust can be found. Never try to remove condensation
using a cleaning cloth or similar, this will most likely smear the optics.
